06 Sep 2012: Report

For Electric Car Batteries, The Race for a Rapid Charge

The amount of time it takes to recharge lithium-ion batteries has been a major impediment to consumer acceptance of electric vehicles. But a host of companies and researchers are working intensively to develop a battery that can recharge in 10 minutes and power a car for hundreds of miles.

by dave levitan

If stopping for gas took five or six hours, would you rethink that road trip? How about an hour? When it comes to electric vehicles, topping up the “tank” does indeed take a long time, one of the primary barriers to more widespread adoption of EVs. So it is no surprise that there is an aggressive push to improve batteries and charging infrastructure, with a goal of making a stop for a recharge no different than a stop for gas.

But pushing a lot of power into a little battery in a short time presents daunting technical challenges. Standard lithium-ion batteries simply aren’t optimized to receive a charge quickly; the car, the plug, and even the wiring would likely need to be revamped in order to enable substantially faster power flow. And there are serious questions about whether the power grid is sufficiently robust to allow massive hits from thousands — or millions — of rapidly charging EVs.

Still, a wide range of companies — from major EV players like General Motors and Nissan to smaller battery manufacturers like Envia, PolyPlus, and A123 Systems — are all pursuing a durable, rapidly rechargeable battery. This means developing higher energy densities, smaller batteries, and — to reduce charging times — lowering internal resistance to ion flow. All these innovations must be achieved while reducing the chances of catastrophic failure, such as the battery catching fire, and keeping down the costs of manufacturing.

Paul Braun, who works on battery materials at the University of Illinois, said a car cruising down the road uses about the same power as 100 hundred-watt light bulbs. Charging rapidly would mean moving the power through the battery 20 times faster than it discharges — a major slug of

Many think rapid charging is coming within 5 to 10 years.

power “many times what is supplied to your house,” Braun said.

Still, progress is being made, and many think rapid charging is coming within 5 to 10 years. Such improvements are sorely needed: Adoption of lower-emissions electric vehicles has been slow, and President Obama’s goal of having 1 million EVs on the road by 2015 may seem overly optimistic at this point.

The longest range EVs on the market now, such as the recently released Tesla Model S, can go up to 300 miles on a single charge, but still cost more than $70,000. The Nissan LEAF, which costs about $30,000, can travel less than 100 miles on a single charge, and the slightly more expensive Ford Focus Electric can travel a similar distance. Tesla’s Model S will yield about 60 miles of range per hour of charging with the best home plug-in systems, and even the LEAF’s smaller battery takes around an hour to charge.

“Part of the drive for the [Chevy] Volt, or even for the [Toyota] Prius, was to minimize changes in consumer behavior,” says Dane Boysen, a program director at the Department of Energy’s Advanced Research Projects Agency-Energy (ARPA-E). “You can buy a Prius and not change your behavior at all.” (The Volt and Prius are hybrid vehicles, sometimes running on electricity and sometimes on gasoline.) But at this point, all-electric vehicles still require significant changes in consumer habits.

So what are the main barriers to reducing charge times?

“One of the key challenges is that the batteries have an internal resistance to flow,” Braun says. Lithium-ion batteries are charged by moving charged particles from a cathode to an anode; pushing those ions into the anode takes time, and forcing them in faster heats up the battery and causes efficiency losses. And if you push too hard, lithium ions may build up in metallic form on the surface of the anode, a phenomenon known as plating, which can drastically shorten a battery’s lifespan. Even without plating, the effects of rapid charging might drop a battery’s life from thousands of cycles down into the hundreds.

“In a conventional battery, the pathways for the ion are very random and not always well connected,” Braun says. “That increases the internal resistance.” His group and others are working on ways to create highly structured internal battery architectures that allow for substantially faster electron and ion transport. Their technology has been licensed by a company called Xerion Advanced Battery Corp.

Gleb Yushin, a materials scientist at the Georgia Institute of Technology, says improving the design of the anode part of the battery, which is most commonly made out of graphite, is an active area of research for both

Scientists are aiming to get between 10 and 50 miles of driving range per minute of charge.

increasing speeds and reducing plating issues. Smaller particles of graphite would enable a faster charge by allowing the ions to move in and out more easily, but small particles also mean lower capacity. Yushin says his lab and many others are trying to make anodes out of materials like silicon and tin that ideally would avoid plating when charged rapidly and would also increase energy density of the batteries.

Others are taking more radical looks at lithium-ion design. Prieto Battery, spun out of research at Colorado State University, uses copper nanowires as the anode and separates them from a cathode array with a polymer rather than the standard liquid electrolyte separator. The three-dimensional structure created by the tiny wires makes the distance a lithium ion must travel much shorter.

These approaches could yield a dramatic cut in charge time. Instead of one mile per minute, Braun says there is a reasonable goal of getting between 10 and 50 miles of driving range per minute of charge. At that pace, even a large battery could top up a 300-mile range in less than 10 minutes.

Braun says that in the lab, at least, very rapid charging is already here. In a paper published in the journal Nature Nanotechnology in 2011, Braun’s group reported achieving a charging rate that would yield a 90 percent full battery in only two minutes, using a three-dimensional nanoarchitecture. Prieto’s designs, meanwhile, could theoretically yield a 400-mile-range battery that could charge in only 10 to 20 minutes. The company thinks it can commercialize its battery within the next year; Braun says that 30 miles per minute of charge is coming within the next two to five years.

“The real question is, can the cost basis of the batteries be low enough to be competitive?” asks Braun. “A 50-percent increase in cost is not going to be tolerated.”

The big car companies are clearly focused on bringing those costs down and improving range. The next Nissan LEAF will reportedly have a longer,

Some companies are pursuing other avenues for rapid charging, like battery swapping.

155-mile range, and a low-end version could cost only around $27,000. GM has invested $7 million into a company called Envia Systems that has achieved an energy density in its battery of two to three times those currently in use, meaning 300-mile or greater range is possible at far lower costs than the Tesla Model S. Envia’s batteries could be used in future versions of the Chevy Volt or other EVs.

It isn’t just the battery that needs to improve. Boysen of ARPA-E says that as rapid charging technology is improved, it’s vital to develop a charging infrastructure.
For example, there is almost no chance in the near future that real rapid charging — on the order of 30 miles per minute of charge or more — will take place when an EV is plugged in at home. The power capabilities of electrical outlets in a home simply aren’t built for the massive current needed to deliver such charges. Instead, the focus is on charging stations, just like gas stations.

Some “rapid charging” stations have already started to spring up around the U.S., with many more of them elsewhere around the world, most notably in Japan. Norway has installed 3,200 stations that offer slower charging of charge EVs, but plans to add 70 rapid charging stations by the end of the year. California-based AeroVironment is installing rapid-charge stations in the U.S. Frank Wong, the company’s director of strategic accounts, says their rapid chargers can take a Nissan LEAF from 20 percent to 80 percent charged in under 30 minutes. The company has more than 20 of these stations installed in Washington and Oregon, with more on the way in Texas and elsewhere. Tesla also recently announced plans for “Supercharger” stations to be installed on high-traffic corridors within a year that will be capable of charging the 300-mile-range batteries within an hour.

If rapid charging stations become ubiquitous, though, they may overload the grid. Braun imagines a rest stop on the New Jersey Turnpike at rush hour, 100 cars all plugging in and trying to charge up in a matter of minutes. “If they were all trying to put in 300 miles of electricity in five minutes, you’re going to need a major power plant sitting next door,” he says.

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Some companies are pursuing other avenues for rapid EV charging, including ideas like battery swapping and wireless charging from current-emitting devices embedded in highways. One company, Better Place, has installed swapping stations in Israel and elsewhere, car wash-like structures where robots replace an EV’s depleted battery with a fresh one. Ideas like this would require substantial infrastructure, however, and aren’t likely to make a dent in the near term. For this concept to take off, some standardization of EV batteries would also be necessary.

All of the attempts to improve charge time basically boil down to the desire to keep using cars as we always have. People don’t complain that it takes a few minutes to put gas into the tank. If EVs are ever going to take over the market, refilling the battery will most likely have to be just as painless.

COMMENTS

After a year and 25k miles in a Nissan LEAF, daily refueling an EV is much more convenient than a gas-burner. I park, plug-in and go. The car is full every morning, no special trip to a fueling station needed because my garage is the station. If someone works at an office, all they need is a 120v outlet for their car while it sits parked all day and it would probably be enough fuel
to get home. A 240v charging station would definitely do the trick.

The situation of 100 cars trying to fill up all at once is unlikely. Those same cars would have been parked somewhere prior to the would-be fueling station trip and plugged-in the whole time. No need for a quick-fill. The trips beyond a car's range is where a quick charge is needed and I use that technology regularly now — CHAdeMO. Twenty minutes gives me 80 percent charge. More of those right now would be a game-changer.

Posted by
Brian Keez
on 06 Sep 2012

Brian, You are REALLY putting the miles on your LEAF! At 13 months, I only have 14K miles on my gen I - LEAF. I am now commuting 95+ miles/day thanks to access to the "quick" charge (<30 min) CHAdeMo charger at Nissan's NA HQ on my way home from work. I can get to 90 percent in about 25 minutes, when the charger automatically shuts down as a safety precaution.

Simply unplug and re-plug the CHAdeMO connector back into the LEAF, and it will go on up to 98 percent in another 5 minutes. Gets me home with 8-12 miles range remaining where I then plug into my home 220V Level 2 charger for 4.5 hours (after the firmware upgrades) and I'm good to go for the return trip to the office the next morning.

Posted by
Don McMunn
on 06 Sep 2012

"When it comes to electric vehicles, topping up the “tank” does indeed take a long time, one of the primary barriers to more widespread adoption of EVs."

Unless you charge it mostly at home and at work while its parked for most of the day. My 2012 Leaf gains 6 miles per hour of 120V (Level 1) charging, 12 miles at 240V (Level 2). If it's parked at work for 8 hours, that's 48 miles you can have on the car when you're ready to go home. The 2013 model will charge twice as fast.

There is definitely a place for public Level 2 and DC fast charging, but it's not quite the constraint people assume it to be.

"And there are serious questions about whether the power grid is sufficiently robust to allow massive hits from thousands — or millions — of rapidly charging EVs."

The utilities aren't worried about this at all, since they would just put in Time-of-Use pricing to shift most of that charging to the overnight hours, when there is plenty of spare electric capacity.

"Adoption of lower-emissions electric vehicles has been slow..."

Just wait until the next gas price spike.

Having driven an EV for almost a year, what strikes me is that capacity isn't really what the battery engineers should be after, it's speed of charging and battery life. A 100 mile range is much easier to live with if you can recharge in 10 minutes. There's not really a need to have a 200 mile range, unless the battery limits you in the number of quick charges you can do. If you can enable faster charging that doesn't harm the battery, you will have a winner, even with a smaller range.

Posted by
Scott Wilson
on 07 Sep 2012

While it's great to see breakthroughs in battery technology, I just don't see the value to the environment of electric cars. Fossil fuels still have to be burned in great amounts in order for these vehicles be power so where is the environmental benefits?

Now, if they can create an electric car with solar panels on the roof that power it, then you would have something!

Posted by
Ken@enviroequipment.com
on 07 Sep 2012

"Fossil fuels still have to be burned in great amounts in order for these vehicles be power so where is the environmental benefits?" This contention is completely incorrect.

A large percentage of electricity is being made from renewable sources such as hydro, solar and wind. This change over to renewables is happening more and more every year.

The one factor almost everybody forgets is that gasoline is a net energy loser. That is, it takes more energy to produce one gallon of gas than the one gallon produces in energy. Also, how do you think oil gets to be gasoline? An oil refinery uses a tremendous amount of electricity to turn that oil into gas.

So, by using gas you are using a fossil fuel (crude oil) and using electricity as well. No matter how you ad it up, a EV still uses less energy and produces less pollution.

Posted by
Kelly R. Olsen
on 09 Sep 2012

Toshiba makes the SCiB used in the 2012 i-MiEV. If you review the spec sheet, the battery is capable of 12C, which means, in theory, the battery can be charged in 5 minutes. The battery capacity is 16 kw-hr so a 12C charge requires 192 kw. And there is the real problem.

The i-MiEV is a small car and every other electric car has a bigger battery so the charger for those cars have to be even bigger. A Tesla with 5 times the battery needs 5 times the charger - which is practically impossible.

I believe the problem is not the battery but the charger which is the limiting factor. As a result, I think the only solution is not a faster changing battery, but a battery swapping method, perhaps like A Better Place or e-buggy.

http://www.toshiba.com/ind/data/tag_files/SCiB_Brochure_5383.pdf

Posted by
Ross Redman
on 09 Sep 2012

Charging locations associated with existing gas stations can use their gas storage tanks to fuel a Generator Set or fuel cell. This can provide the power requirements of the electric vehicles. The waste heat from the Genset or fuel cell can be used to heat or cool the refrigeration cases, storefront and restrooms. These GS's and FC's will be in demand and improvements can be made to the combined heat and power plant in order to make them for the residential market. As "Garbage digesters" become more prevalent, a residence can use the products brought home to supplement fuel for the Genset or fuel cell. Therefore, with enough local GS and FC installations much of the existing electrical grid will be able to carry future loads.

Posted by
Ray Alfini
on 10 Sep 2012

Fossil fuels DON'T have the be burnt to provide the electricity. With a gasoline engine, you've not got a lot of other options. Bio-fuels yes but they come with their own problems at present.

But with an electric vehicle, that electricity can come from solar, wind, geothermal, or any number of other non-fossil fuel alternatives. If you're in a part of the country where your electricity comes from coal, then ya, not a lot of environmental benefits to going electric, but if not, then big benefits.

Posted by
Robert Dinse
on 14 Sep 2012

I just don't understand. Since the U.S. is now a net exporter of natural gas, why we don't have the push for NG cars is beyond me. Take for example the GM Volt. General Motors takes about a 30k loss every time a Volt sells. The automotive industry doesn't have to retrofit anything to accommodate NG cars. It’s just as simple as changing your gas dryer to except propane (just a different nozzle). Just look at the plentiful amount of forklifts out there using propane gas vs. diesel fuel. They all made a simple conversion to accommodate this. Along with the emissions compliance that NG offers is darn near second to none. And vs. electric cars, re-charging them doesn't require dirty coal plants to remain at full load to re-charge them. Also taking into account, with NG cars you don't loose performance. Also worth nothing that the several people I work with that have electric cars sometimes have to shut down their heater in the middle of winter just to make it home. I challenge everyone reading this response to contact their state reps and demand more options on our highways. NG is cheap, clean, less expensive, and you probably already have NG ran through your garage that can be modified to "re-charge your car.

Posted by
Brad Warner
on 25 Sep 2012

In Korea they commonly use NG in the same cars they export to the U.S. with gasoline engines. Honda sells a NG Civic here and one of the Ridgefield Washington council members has had one for years that refuels off a compressor in his garage using the home's natural gas line.

Posted by
Pat Campbell
on 16 Jan 2013

induction plate in each traffic lane, to charge the induction plate installed on your frame rails, would end all range problems, with electric cars. why is this never mentioned? small thorium powered plants to power the embedded rail , would end the problem, check this out for yourself, the portals are not blocked the choices are. start reading about the oil tree, tied to the tax tree, tied to choices. thanks,

Posted by
kf allen
on 06 Feb 2013

Comments have been closed on this feature.

ABOUT THE AUTHORDave Levitan is a freelance journalist based in Philadelphia who writes about energy, the environment, and health. His articles have been published by Reuters, SolveClimate, IEEE Spectrum, and Psychology Today. In previous articles for Yale Environment 360, he has written about the potential of self-driving cars and about vehicle-to-grid technology involving electric cars.MORE BY THIS AUTHOR

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